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Abstract:
We report the observation of the generation and routing of single plasmons
generated by localized excitons in a WSe$_2$ monolayer flake exfoliated onto
lithographically defined Au-plasmonic waveguides. Statistical analysis of the
position of different quantum emitters shows that they are $(3.3 \pm
0.7)\times$ more likely to form close to the edges of the plasmonic waveguides.
By characterizing individual emitters we confirm their single-photon character
via the observation of antibunching of the signal ($g^{(2)}(0) = 0.42$) and
demonstrate that specific emitters couple to the modes of the proximal
plasmonic waveguide. Time-resolved measurements performed on emitters close to,
and far away from the plasmonic nanostructures indicate that Purcell factors up
to $15 \pm 3$ occur, depending on the precise location of the quantum emitter
relative to the tightly confined plasmonic mode. Measurement of the point
spread function of five quantum emitters relative to the waveguide with <50nm
precision are compared with numerical simulations to demonstrate potential for
higher increases of the coupling efficiency for ideally positioned emitters.
The integration of such strain-induced quantum emitters with deterministic
plasmonic routing is a step toward deep-subwavelength on-chip single quantum
light sources.